Dipole operator constraints on composite Higgs models

Flavour- and CP-violating electromagnetic or chromomagnetic dipole operators in the quark sector are generated in a large class of new physics models and are strongly constrained by measurements of the neutron electric dipole moment and observables sensitive to flavour-changing neutral currents, such as the $B\to X_s\gamma$ branching ratio and $\epsilon'/\epsilon$. After a model-independent discussion of the relevant constraints, we analyze these effects in models with partial compositeness, where the quarks get their masses by mixing with vector-like composite fermions. These scenarios can be seen as the low-energy limit of composite Higgs or warped extra dimensional models. We study different choices for the electroweak representations of the composite fermions motivated by electroweak precision tests as well as different flavour structures, including flavour anarchy and $U(3)^3$ or $U(2)^3$ flavour symmetries in the strong sector. In models with "wrong-chirality" Yukawa couplings, we find a strong bound from the neutron electric dipole moment, irrespective of the flavour structure. In the case of flavour anarchy, we also find strong bounds from flavour-violating dipoles, while these constraints are mild in the flavour-symmetric models.Comment: 30 pages, 2 figures, 11 tables. v3: Misprints in table 8 corrected. Numerics and conclusions unchange

On the Equivariant Tamagawa Number Conjecture for Tate Motives, Part II

Let K be any finite abelian extension of Q, k any subfield of K and r any integer. We complete the proof of the equivariant Tamagawa Number Conjecture for the pair (h⁰(Spec(K))(r),Z[Gal(K/k)])

Demo: Linux Goes Apple Picking: Cross-Platform Ad hoc Communication with Apple Wireless Direct Link

Apple Wireless Direct Link (AWDL) is a proprietary and undocumented wireless ad hoc protocol that Apple introduced around 2014 and which is the base for applications such as AirDrop and AirPlay. We have reverse engineered the protocol and explain its frame format and operation in our MobiCom '18 paper "One Billion Apples' Secret Sauce: Recipe of the Apple Wireless Direct Link Ad hoc Protocol." AWDL builds on the IEEE 802.11 standard and implements election, synchronization, and channel hopping mechanisms on top of it. Furthermore, AWDL features an IPv6-based data path which enables direct communication. To validate our own work, we implement a working prototype of AWDL on Linux-based systems. Our implementation is written in C, runs in userspace, and makes use of Linux's Netlink API for interactions with the system's networking stack and the pcap library for frame injection and reception. In our demonstrator, we show how our Linux system synchronizes to an existing AWDL cluster or takes over the master role itself. Furthermore, it can receive data frames from and send them to a MacBook or iPhone via AWDL. We demonstrate the data exchange via ICMPv6 echo request and replies as well as sending and receiving data over a TCP connection.Comment: The 24th Annual International Conference on Mobile Computing and Networking (MobiCom '18

Completing the hadronic Higgs boson decay at order αs4\alpha_s^4

We compute four-loop corrections to the hadronic decay of the Standard Model Higgs boson which are induced by effective couplings to bottom quarks and gluons, mediated by the top quark. Our numerical results are comparable in size to the purely massless contributions which have been known for a few years. The results presented in this paper complete the order $\alpha_s^4$ corrections to the hadronic Higgs boson decay.Comment: 15 pages, 2 figure

Hadronic Higgs boson decay at order αs4\alpha_s^4 and αs5\alpha_s^5

We compute corrections to the decay of the Standard Model Higgs boson to hadrons, to the fourth order in the strong coupling constant $\alpha_s$. We use an effective theory in which the Higgs boson couples directly to bottom quarks and to gluons, via top quark--mediated effective couplings. Numerically, our results are of a comparable size to the previously-known "massless" contributions and complete the order $\alpha_s^4$ corrections to the hadronic decay of the Higgs boson. In these proceedings we also provide an independent cross check of the gluonic Higgs boson decay at order $\alpha_s^5$.Comment: 6 pages, 0 figures. Contribution to the proceedings of the XXV International Workshop on Deep-Inelastic Scattering and Related Topics (DIS2017), 3-7 April 2017, University of Birmingham, UK. V2: Reference adde

The Beta-Hyperbolic Secant (BHS) Distribution

The shape of a probability distribution is often summarized by the distribution's skewness and kurtosis. Starting from a symmetric parent density f on the real line, we can modify its shape (i.e. introduce skewness and in-/decrease kurtosis) if f is appropriately weighted. In particular, every density w on the interval (0; 1) is a specific weighting function. Within this work, we follow up a proposal of Jones (2004) and choose the Beta distribution as underlying weighting function w. Parent distributions like the Student-t, the logistic and the normal distribution have already been investigated in the literature. Based on the assumption that f is the density of a hyperbolic secant distribution, we introduce the Beta-hyperbolic secant (BHS) distribution. In contrast to the Beta-normal distribution and the to Beta-Student-t distribution, BHS densities are always unimodal and all moments exist. In contrast to the Beta-logistic distribution, the BHS distribution is more êexible regarding the range of skewness and leptokurtosis combinations. Moreover, we propose a generalization which nests both the Beta-logistic and the BHS distribution. Finally, the goodness-of-fit between all above-mentioned distributions is compared for glass fibre data and aluminium returns. --

To Segregate or to Integrate: Education Politics and Democracy

The governments of nearly all countries are major providers of primary and secondary education to its citizens. In some countries, however, public schools coexist with private schools, while in others the government is the sole provider of education. In this study,we askwhy different societiesmake different choices regarding the mix of private and public schooling. We develop a theory which integrates private education and fertility decisionswith voting on public schooling expenditures. In a given political environment, high income inequality leads to more private education, as rich people opt out of the public system. Comparing across political systems, we find that concentration of political power can lead to multiple equilibria in the determination of public education spending.

Towards a Simplified Dynamic Wake Model using POD Analysis

We apply the proper orthogonal decomposition (POD) to large eddy simulation data of a wind turbine wake in a turbulent atmospheric boundary layer. The turbine is modeled as an actuator disk. Our analyis mainly focuses on the question whether POD could be a useful tool to develop a simplified dynamic wake model. The extracted POD modes are used to obtain approximate descriptions of the velocity field. To assess the quality of these POD reconstructions, we define simple measures which are believed to be relevant for a sequential turbine in the wake such as the energy flux through a disk in the wake. It is shown that only a few modes are necessary to capture basic dynamical aspects of these measures even though only a small part of the turbulent kinetic energy is restored. Furthermore, we show that the importance of the individual modes depends on the measure chosen. Therefore, the optimal choice of modes for a possible model could in principle depend on the application of interest. We additionally present a possible interpretation of the POD modes relating them to specific properties of the wake. For example the first mode is related to the horizontal large scale movement. Besides yielding a deeper understanding, this also enables us to view our results in comparison to existing dynamic wake models